The intent of this study is to demonstrate the effect of the organization of practice on the adequacy of primary medical care. In comparing the systems delivering primary care, this study addresses two issues. What are the barriers or stimulants to the use of services encountered by the potential patient prior to entry into the health care system? What is the impact of medical care on the patient once he has entered the system? The research method used to answer the first question is a population survey based on a probability sample of households. Answers to the second question are being sought through the application of the "indicator case model", in which various aspects of both the "cure" and "care" functions of medical services are measured. Data derived from this study will indicate which systems most adequately fulfill the health care needs of various segments of the population. It is anticipated that no one system will be equally effective for all groups, but that each form of practice will exhibit certain merits under varying circumstances. It is the differences and relative effectiveness which will be documented through the methods described.